This invention relates to a radiator for a semiconductor chip, particularly for a highly integrated semiconductor chip such as LSI chip and VLSI chip.
In recent years, semiconductor chips have been sealed with plastic to protect circuitry from moisture and other damage. Plastic encapsulation of the semiconductor chip is generally effected by transfer molding or the potting method. In the latter, only the active surface of the semiconductor chip is sealed by dropping plastic on the active surface. With the potting method, however, moisture can not be effectively prevented because the remainder of the semiconductor chip is exposed to the atmosphere. For that reason, plastic encapsulation of the semiconductor chip is effected by transfer molding in most cases. With transfer molding, the entirety of the semiconductor chip is enclosed with plastic such as epoxy resin and silicone resin.
However, there is a problem with plastic encapsulation by transfer molding. More particularly, it is hard to release heat from the semiconductor chip because the entirety of the semiconductor chip is sealed with plastic. This problem becomes serious as the integration of circuit of semiconductor chip progresses and the electric power per unit area of semiconductor chip increases. A plastic encapsulation configuration having radiation fins has been proposed to address this problem. However, cooling through plastic encapsulation is not very effective because plastic has a low heat conductivity. In addition, the provision of such radiation fins to plastic encapsulation hinders the miniaturization of the semiconductor package which mainly comprises the sealed semiconductor chip and leads extending outwardly therefrom.
In addition, another problem with semiconductor chips as the integration of internal circuit progresses has been discovered. A highly integrated semiconductor chip requires electrical protection. Otherwise, it is apt to become charged with external static electricity. Indeed, the internal circuit can be destroyed by a spark if a charged human body or the like touches the semiconductor chip or the internal circuit may erroneously operate due to current induced by pulsive electromagnetic wave noise. In addition, the ground potential of the semiconductor chip tends to deviate due to the inductance of leads.